Proto-Celtic *-ākos

→ English bog (derived)

→ English barnacle (derived)

→ English Kelleher (derived)

→ Welsh -og (inherited)

→ Welsh ceinach (mention)

→ Irish -ach (inherited)

→ Irish -óg (derived)

→ Scottish Gaelic -ag (derived)

→ Scottish Gaelic -ach (inherited)

→ Manx -ag (derived)

→ Manx -agh (inherited)

→ Middle Irish -ach (inherited)

→ Old Irish -ach (inherited)

→ Old Irish -óc (derived)